Effect of plastic deformation on the structure and properties of the Ti/TiB composite produced by spark plasma sintering

A Ti/17 vol % TiB composite material is produced by spark plasma sintering of a mixture of titanium and 10 wt % TiB2 powders at a temperature of 1000°C. Multiaxial isothermal forging is performed at t = 850°C to enhance the mechanical properties of the composit

Neutron lifetime measurements using gravitationally trapped ultracold neutrons

Our experiment using gravitationally trapped ultracold neutrons (UCN) to measure the neutron lifetime is reviewed. Ultracold neutrons were trapped in a material bottle covered with perfluoropolyether. The neutron lifetime was deduced from comparison of UCN losses in the traps with different surface-to-volume ratios. The precise value of the neutron lifetime is of fundamental importance to particle physics and cosmology. In this experiment, the UCN storage time is brought closer to the neutron lifetime than in any experiments before:the probability of UCN losses from the trap was only 1% of that for neutron beta decay. The neutron lifetime obtained,878.5+/-0.7stat+/-0.3sys s, is the most accurate experimental measurement to date.Comment: 38 pages, 19 figures,changed conten

Structure and hardness of B2 ordered refractory AlNbTiVZr0.5 high entropy alloy after high-pressure torsion

High-pressure torsion (HPT) at room temperature was applied to an AlNbTiVZr0.5 refractory high entropy alloy. In the initial as-cast condition the alloy was composed of a coarse-grained B2 matrix phase and a continuous network of C14 Laves phase particles with the volume fraction of 19%. HPT resulted in the formation of a nanocrystalline structure in the B2 matrix with an average size of grains/subgrains of 25 nm after 5 revolution

Structure and mechanical properties of B2 ordered refractory AlNbTiVZrx (x=0-1.5) high-entropy alloys

Structure and mechanical properties of the AlNbTiVZrx (x=0; 0.1; 0.25; 0.5; 1; 1.5) refractory high-entropy alloys were investigated after arc melting and annealing at 1200°C for 24 h. The AlNbTiV alloy had a B2 ordered single phase structure. Alloying with Zr resulted in (i) change of the degree of order of the B2 phase; and (ii) precipitation of the Zr5Al3 and C14 Laves ZrAlV phase

Aging behavior of the HfNbTaTiZr high entropy alloy

The HfNbTaTiZr high entropy alloy was produced by vacuum arc melting, homogenized at 1200 C, and annealed at 600-1000 C for 1-100 h. Structure and microhardness of the annealed alloy were investigated. A strong increase of microhardness after aging treatment at 600 C was found. Formation of second hcp phase particles in the bcc matrix after annealing at 600 and 800 C was also revealed. Effect of precipitation of second phase particles on microhardness was analyze

Effect of thermomechanical processing on microstructure and mechanical properties of the carbon-containing CoCrFeNiMn high entropy alloy

Microstructural evolution during cold sheet rolling to 80% thickness strain and annealing at 600-1100° C for 30 min of the CoCrFeNiMn high entropy alloy doped with 1 at.% of C and resulting mechanical properties of the alloy are reporte

Measurement of the neutron lifetime using a gravitational trap and a low-temperature Fomblin coating

We present a new value for the neutron lifetime of 878.5 +- 0.7 stat. +- 0.3 syst. This result differs from the world average value (885.7 +- 0.8 s) by 6.5 standard deviations and by 5.6 standard deviations from the previous most precise result. However, this new value for the neutron lifetime together with a beta-asymmetry in neutron decay, Ao, of -0.1189(7) is in a good agreement with the Standard Model.Comment: 11 pages, 9 figures; extended content with some correction

Prediction of strength characteristics of high-entropy alloys Al-Cr-Nb-Ti-V-Zr systems

Experimental evaluations of mechanical properties and investigations microstructure are time-intensive, requiring weeks or months to produce and characterize a small number of candidate alloys. In this work, machine learning approaches were used for prediction yield strengths of high-entropy alloys Al-Cr-Nb- Ti-V-Zr system at 20, 600 and 800 C. Surrogate prediction model was built with support vector regression algorithm by a dataset including more 30 alloys Al-Cr-Nb-Ti-V-Zr system. Four model alloys were fabricated for testing the surrogate model by vacuum arc melting. After that model alloys were annealed in a quartz tube at 1200 C 10

Copper Sorption by Coal Substances from Aqueous Solutions

The copper cations sorption by brown coal, humic acids and residual coal samples after the extraction of humic acid was studied by using the methods of spectroscopy FT-IR, EPR, Solid State CP/MAS 13C-NMR. Samples of lignite (brown coal) of the Tisulsky deposit (TL) of Kansk-Achinsk brown coal basin (Russia), its naturaloxidized form (NOLF), as well as samples of the humic acids (HA) extracted from them, and the residual coal after the extraction of humic acids (RC) were used as sorbents. The copper cations sorption process by the investigated samples depends on contribution of several mechanisms in varying degrees. It may be an ion exchange; complexation with the functional groups of the electron donor; complexation to form the bond Mez+ – HA due to the presence of the free π-electrons on the surface. The quantity of adsorbed copper cations depends on the functional and structural composition of the investigated samples. The copper cations sorption by the coals, humic acids and residual coals reduces the number of paramagnetic centers in the samples and the intensity of the NMR spectra. The copper cations sorption by HA from TL is determined by the significant contribution of the ion exchange process. HA from NOLF; initial TL and NOLF; RC TL and RC NOLF sorb copper cations mainly due to the formation of complexes with individual functional groups and the negatively charged surface portions. The data of 13C-NMR and EPR studies have shown that the aromatic structures make the main contribution to the complexation